Electric Charge and Static Electricity

Unit 7, Lesson 3

Accessing Prior Knowledge

Discuss…..

What particle of an atom has a negative charge?

 What are forces?

 Give an example of a force that acts over a distance.

Electric Charge

• Electric charge- a property that leads to electromagnetic interactions between the particles that make up matter• Can be a positive charge, a negative charge, or no

charge

Ion: when an atom is negatively or positively charged

What affects the electric force between two objects?

Any two charged objects exert a force on each other called an electric force

• This is like gravity- they act on each other without touching• However, gravity is only a pull, electric force can pull OR push

Charge• Like charges repel, opposite charges attract• The amount of charge effects the strength

Distance

• The distance between the two objects effects the size of the electric force-

• Closer together = stronger force

How can an object become charged?

Objects become charged when their atoms gain or lose electrons. The three ways this can happen are…

1. By Friction• When two objects are rubbed together- this causes a transfer of

electrons between the objects• EX: rubbing a balloon on your head

2. By Contact• If a charged object and an uncharged object touch, the charged

object can transfer some of its charge to the area it touches• EX: hair standing up when touching a Van de Graaff generator

3. By Induction• Rearranging the charges in an object without touching it. • EX:

What is static electricity?

• Static electricity- the extra buildup of electric charge on an object

• Charges that build up as static electricity eventually leave the object. This is known as Electric discharge

• EX: Lightning

What materials affect the flow of charge?

Conductors A material through which charges can move freely EX: metal

(mostly copper is used in wires) Insulators

A material through which charges can NOT move freely EX: Plastic, rubber, glass, and dry air

(plastic is used on the outside of wiring) Semiconductors

Materials are able to control the flow of charge. Used to process electrical signals in different ways EX: Silicon (computer chips)

How is charge conserved?

Atoms gain or lose electrons from other objects

Electrons are not really lost, they are transferred Electrons can not be created or destroyed